Method of casting wearing part having retaining structure

ABSTRACT

A method of casting a wearing part having a body of a hard and relatively brittle wear-resistant material and a retaining structure located within the body by coating the retaining structure with a separating material before pouring the molten material of the wearing part around the retaining structure.

United States Patent Inventor Edwin 8. Long New Berlin. Wis.

Appl. No. 852,036

Filed Aug. 21,1969

Patented July 27, 1971 Assignee Nordberg Manufacturing Company Milwaukee, Wis.

METHOD OF CASTING WEARING PART HAVING RETAINING STRUCTURE 3 Claims, 2 Drawing Figs.

US. Cl 164/75, 164/100, 241/291 Int. Cl 822d 19/02 Field of Search 164/75,

{56] References Cited UNITED STATES PATENTS 1,025,817 v5/1912 Luckenbach 164/100 1.343.017 6/1920 Ware v .7 164/10 3.191152 6/1965 Webbere... 164/75 3,276,082 10/1966 Thomas 164/75 X Primary EXGI1I1I|TJ. Spencer Overholser Assistant Examiner-John E. Roether Attorney- Parker, Carter & Markey ABSTRACT: A method of casting a wearing part having'a body of a hard and relatively brittle wear-resistant material and a retaining structure located within the body by coating the retaining structure with a separating material before pouring the molten material of the wearing 'part around the retaining structure.

METHOD OF CASTING WEARING PART HAVING RETAINING STRUCTURE SUMMARY OF THE INVENTION This invention is concerned with a method of casting a wearing part having a body of a hard and relatively brittle wear-resistant material and a retaining structure which functions to maintain the body dimensionally stable in the event the body ruptures or cracks. Because the purpose of the retaining structure is to maintain the dimensional stability of the body of the wearing part in the event that it ruptures or cracks during use, it is important that the retaining structure does not become sintered or fused to the material of the body. If the retaining structure, by sintering, fusing or otherwise, becomes an integral part of the body of hard and relatively brittle material, it may also break upon the application of severe forces to the body. Problems have arisen in keeping the retaining structure independent of the wearing material of the body is cast around the retaining structure. Various methods of coating the retaining structure to prevent adhesion of the rods of the retaining structure to the body of wearing material have been tried, but generally these methods have not been entirely successful. Therefore, it is an object of this invention to provide a method of casting a hard and relatively brittle wear-resistant material around a retaining structure while preventing the retaining structure from adhering to or become an integral part of the cast material.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated more or less diagrammatically in the following drawings wherein:

. FIG. 1 is a cross section view taken througha crusher liner segment having retaining rods cast in accordance with the method of this invention; and

FIG. 2 is a block flow diagram showing the steps of coating the retaining rod structure.

DESCRIPTION OF THE PREFERRED EMBODIMENT The method of this inventionis shown in connection with the casting ofa liner segment used in a gyratory crusher of the primary type. This method may also be used for casting other types of wearing parts including, but not limited to, bowl liners and mantles for gyratory and cone crushers. The drawings show a liner segment 11 of generally rectangular shape. The liner has an outer surface 13 which is mounted against the bowl ofa crusher (not shown) and an inner wearing surface 15 which is opposed to the head of a crusher (not shown) and engages the material to be crushed.

The liner segment 11 may be cast from a hard and relatively brittle material such as pearlitic, carbidic white cast iron or martensitic, carbidic, chrome-nickel alloy iron sometimes known as NIHARD. Castings of such metals are known to be relatively brittle and hard and have good wearing characteristics.

Positioned in the liner segment casting is a retaining structure 17 which is formed by a rod 19 bent into a series of loops, one formed inside the other. Spacers 21 and 23 may be provided to maintain the spacing of the loops. In addition, back spacers 25 are provided which extend to the outer surface 13 of the liner segment. The back spacers serve to support and center the retaining structure in the body of hard and relatively brittle material which is poured around the retaining structure. The retaining rod may be formed of a low carbon steel having a high tensile strength.

In order to prevent the rod of the retaining structure from sintering or fusing to the molten material of the liner segment during casting of this material about the retaining structure, the' retaining structure is coated with a separating material. Before the coating is applied, it may be desirable to prepare the surfaces of the rod by conventional blasting or pickling methods. Stress relieving may be desirable on complex retainin structures.

he method of coating includes a first step of brushing or otherwise applying to the rod, a uniform coating of Delta Core Oil No. 800 or an equivalent thereof. Next, a mixture consisting of, by weight, to percent silica sand of fineness about 45 to 50, l to 10 percent silica flour and l to 5 percent plumbago, is sprinkled on or otherwise applied uniformly to the surfaces of the oil-coated retaining rod. The coated retaining structure is then heated at about 450 F. until the coating is hard and dry. This method usually results in an excellent sand coating 27 of about l/32-inch thickness. If a greater thickness is desired, the procedure may be repeated. Generally it has been found desirable to apply two or three coats to the retaining structure. After the retaining structure is suitably coated, the molten material of the body is cast about the retaining rod structure to form the liner segment.

The hard crust or coating 27 surrounding the rod of the retaining structure prevents the cast metal of the liner segment from becoming sintered or fused to this rod. The crust may permit relative movement of the liner segment with respect to the rod of the retaining structure when the liner segment cools so that internal stresses due to the presence of the retaining structure are minimized. After the liner segment has cooled, there may be very little clearance, if any, between the retaining 'rod and the casting itself. However, it should be understood that the purpose of the coating is not necessarily to provide sufficient clearance to allow relative movement between the retaining structure and the metal of the casting but is mainly to prevent the retaining rod from sintering or fusing to the metal of the casting.

Whereas the method of this invention has been described in connection with the casting of a liner segment for a gyratory crusher, it should be understood that the method is adapted to other wearing parts in which a casting of a hard and relatively brittle wear-resistant material is formed about a retaining structure of rods of high tensile strength. It should also be understood that although a specific formula has been listed for the coating material, this formula may be varied to some extent without departing from the teachings of this invention.

I claim:

1. A method of casting a retaining rod in a wearing part to prevent the retaining rod from becoming sintered or fused to the wearing part including the steps of:

coating the retaining rod with core oil,

applying generally uniformly to said core-oil-coated retaining rod, a composition consisting essentially of, by weight, about 85 to 95 percent silica sand of fineness about 45 to 50, about I to 10 percent silica flour and about I to 5 percent plumbago,

heating the composition-coated retaining rod until the coating is dry and hard, and

pouring the molten metal of the wearing part completely around the composition-coated retaining rod, solidifying the molten metal of the wearing part to wholly incorporate the retaining rod in an unsintered or unfused condition within the wearing part.

2. The method of claim 1 further characterized in that the composition-coated retaining rod is heated at a temperature ofapproximately 450 F. to dry the coating.

3. The method of claim 1 further characterized in that two or three thicknesses of the composition coating are applied to the retaining rod before the molten metal is poured around it. 

2. The method of claim 1 further characterized in that the composition-coated retaining rod is Heated at a temperature of approximately 450* F. to dry the coating.
 3. The method of claim 1 further characterized in that two or three thicknesses of the composition coating are applied to the retaining rod before the molten metal is poured around it. 